1. Field
The disclosed technology relates to a luminance correction system, and more particularly, to a luminance correction system applied to organic light emitting display devices.
2. Description of the Related Technology
An organic light emitting display device is a kind of flat panel display device which uses an organic compound as a light emitting material in a light emitting component of the display. Due to the advantages of an organic light emitting display device, including high luminance and color purity, reduced thickness, lightweight and low power consumption characteristics, it is expected that the organic light emitting display device will be used for various types of display devices such as portable display devices, and the like.
The organic light emitting display device generates a data signal having a voltage for each gray level based on a reference gamma voltage, and displays an image corresponding to the generated data signal. As a result, the luminance of each corresponding component of different display devices may be different from a desired luminance due to variations that result from manufacturing.
Where the luminance of a manufactured display device does not meet standards of desired luminance, the display device is considered to be defective and not usable. Therefore, correction of luminance of a flat panel display device based on a measured luminance following completion of the manufacturing process to a desired luminance value may reduce the number of display devices which are deemed defective.
However, if only the luminance were to be corrected, white balance could be distorted due to the efficiency disparity among red, green, and blue pixels. Therefore, in addition to luminance correction it may be necessary to correct color coordinates.
Generally, correction of luminance and color coordinates assumes that the power signal (ELVDD or the like) applied to the organic light emitting display device is always applied at a constant level. Conventionally, DC-DC converters that generate and output power for driving the display were built in, and thus the power signal could maintain a constant level for all displays regardless of the variation in output voltage between the DC-DC converters.
However, DC-DC converters have recently been mounted external to the display. In such configurations, variations occur in power signal levels among displays. As a result, there are variations in luminance.